Antenna sector scanning control



July 29, 1952 BE. MILLER I ANTENNA SECTOR SCANNING CONTROL Filed boy. a,1945 Xiuk 2 5m ms;

EEmmIF INVENTOR EDWARD E. MILLER ATTORNEY Patented July 29, 1952 ANTENNASECTOR SCANNING CONTROL Edward Ernst Miller, Medford, Mass., assignor,by mesne assignments, to the United States of America as represented bythe Secretary of the Navy 1 a Application October 8, 1945, Serial No.621,127

This invention relates to a system for controlling the oscillatoryscanning of an antenna through a sector of its possible scanning angleand more particularly to such a system in which the angle of scan andthe orientation of the center of the scanned sector may be varied as maybe found to be desirable.

In the operation of radio echo detection apparatus it is frequentlydesirable to cause the antenna of the apparatus to scan back and forththrough a relatively small angle. By avoiding the necessity of wastingtime in the scanning of areas of no interest, a given group of signalscan be scanned more slowly and at the same time more frequently over theparticular area of interest. Since successive traces will then overlapin greater number, and less time will be consumed between scans, thesensitization of the screen of the plan position indicator may be builtup so that faint and fluctuating signals will be seen on a greaterpercentage of scans than would be seen if it were necessary to scanthrough three hundred sixty degrees with each sweep.

An object of this invention is to provide an electrical system forcausing the armature of a motor to cyclically scan through an arc.

Another object of this invention is to provide an electrical system forcausing an antenna or the like to cyclically scan a sector of thepossible scanning angle through which the antenna may be rotated.

Still another object of this invention is to provide in an electricalsystem of the class described, means for varying the size of the anglethrough which the antenna is caused to scan.

A further object of this invention is to provide in an electrical systemof the class described, means for adjusting the orientation of themidpoint of the angle through which the antenna is caused to scan.

A particular object of this invention is to provide a novel circuit forcausin an antenna to cyclically scan through a predetermined sectorhaving a gas tube for controlling the reversal of the direction ofrotation of the antenna.

Other objects and advantages of this invention, as well as itsconstruction, arrangement, and operation will be apparent from thefollowing description and claims in connection with the accompanyingdrawing, in which, the figure is a circuit diagram of a preferredembodiment of the invention.

Referring to the figure, there is shown an antenna 20, the motion of,which it is desired to control. Antenna 2!) is geared to the armature 14Claims. (01. s1s-2s2) of a suitable drive motor 2| which is capable ofrotating antenna 20 in a clockwise or counterclockwise direction undercontrol of an automatic reversing switch 22 actuated by a relay 23,switch 22 being disposed in the armature circuit of motor 2| and adaptedto control the direction of current therethrough. Operation of relay 23is controlled by a second relay 3| having the coil 32 thereof/connectedin the plate circuit of a gas tube 40 of the 2050 type. A third relay 24.is provided to allow suitable ganged switches 25, 2G and 21 to open themotor armature and field' circuits whenever ganged control switches '28,29 and 30 are placed in a stop position. .Relay 24, being connectedacross the power. line will always be energized except when switch. 28is placed in a.stop position.

It will readily be apparent from the figure that with the placementof'switch 30 in a spin position the plate circuit of tube 40 will beopened, thereby causing relay 3| to be inoperative. and preventingreversing action which normally occurs due to operating the relaythrough action of tube 40.. Although relay 24 is normally energizedirrespective of the action of relay 3|, relay 23 is alternatelyconnectedacross the power line and disconnected therefrom inaccordancewith the position of movable contact 33 of relay 3|. In thepositionshown in the figure, relay 23 is deenergized so that switch 22is in the down position. Energization of coil 32 of relay 3| results ina switching action of relay 3|, thereby energizing relay 23 and causingswitch '22 to assume a position opposite to that illustrated, with aresultant reversal of the direction of' rotation of antenna 20. t 3 1 Asheretofore stated, relay 3| is controlled by gas tube 40, coil 32 ofrelay 3| beingconnected in the plate circuit of tube 40. An RrG circuit.36 is connected across coil 32 to prevent chatter of relay 3|. Whencurrent flows through coil 32, contact 33 will touch contact 35, butwhen coil 32 is deenergized contact 33 will be connected to contact 34"as illustrated. Energization and deenergization of coil 32 depend uponthe firing of tube 40, the coil being energized when tube 40 fires anddeenergized when tube 40 is, caused to cease firing. A transformer 31having secondaries 38 and 39 supplies A. C. voltage to the oathode 43,plate 42, and heater 44 of tube 40. A balance potentiometer 45 isconnected between grid 4| and cathode 43 to impress A. C. voltage oncathode 43. A feed-back circuit connected to member 33 of relay 3 lcauses grid 4| to be supplied with a negative A. C. voltage whenevertube 413 does not fire and with a positive voltage when the tube firesby reversing the flow of current through a potentiometer 41 providingfor adjusting the angle of scan through which it is desired to causeantenna 20 to oscillate. As shown, potentiometer 41 is connected betweenarm 33v of relay 3| and a half-voltage point between two'resistances48and 49 connected across the power line. More specifically, the switchingof arm 33 from one position to the opposite position changes therelative phase of the grid feed-back voltage one hundred eighty degreeswith respect to its previous phase relationship. This feed-back circuit,therefore, places a nega: tive voltage on grid 4| when plate 42 ispositive for one position of arm 33 and a positive voltage on grid 4|for the opposite position (alarm 33 when plate 42 is positive.

In addition to the voltage impressed upon grid 4| by the feed-backcircuit, a, selenium disc rectifier 50 and filter capacitor 51'areconnected across secondary winding 39 to. supply a fixed negative I).C; voltage bias upon grid 4|- It is apparent, therefore that two.voltages inseriesmake up the bias upon grid 4!, one being a fixed D. C.voltage making the grid more negative and the, other an A. C. voltagewhich opposes the D. C. voltage. by making the grid more positive duringthe halfcycle when the plate of. tube 40 is positive. An error voltage,the amplitude of which, is proportional to the sine of the angle, throuh which antenna 20. is. caused to rotate is supplied by a controltransformer 52, preferably of the Selsyn type, and impressed upon grid.througha suitable potentiometer 53. All of the voltages impressed upongrid 4.! pass through potentiometer 63 which is providcd'with a handle54 for dete'rmining the:particular sector. in azimuth to be sca'niiedl.In operation, thesense of the feedeback voltage: is such. that: if thegrid becomesiust post tive. enough to fire the tubeandenergize relay-3|the. resulting change in feed-back voltage.- will make.v the grid stillmore positive. Antenna 20, and selsyn 52 'which is rotated thereby-mustmove until a. sufficient negative errorvoltage is gen- 1 erated tocancel the. feed-back, whereupontube *4.0.-ce asesfiring and relay 3! isdeenergized and the resulting changeinfeed-back makes thegrid still morenegative. Thus, the more feedeback voltage supplied the wider will, bethe scan. through which antenna 20 will rotate. By-varyins potentiometer41 the scan can. be changed from abare minimum to a value approachingone hundred, eighty degrees. By varying the position of thepick-ofipoints-of potentiometer 53 the-posh tion of the center of scan may bevaried through three hundred sixty degrees, while the setting ofpotentiometer 41 varies the widthof. scan from approximately-two degreesto one hundred forty degrees. 1

Asthe voltageongrid 4| is raised to the point wheretube 40 fires, theaverage current in coil 32 suddenly jumps from zero. to asubstantiallconstant value and does not increase,v further even though the grid .bedrivenmore positive. Lowering of the grid voltage. tocut-oif causes thetube to cease firing thereby suddenly dropping the coil current in relay3| back to zero.

I A thermal relay 55 is provided to delay the plate voltage in tubeill-until the filament of the.

tube is properly heated in order to prevent de- 55. issuflicientlyheated to close switch 51. T11 1- mal relay 55 is adjusted to allowsufiicient time for the filament of tube 46 to become properly heatedbefore relay 55 closes.

While a specific embodiment of this invention has been disclosed anddescribed, it is to be understood that various modifications and changesmay be made in this invention without departing from the spirit andscope thereof as set forth in the appended claims.

What is claimed is:

1. An electrical system for causing the armature of a motor to oscillatethrough a given are comprising switching means for reversing thedirection of current fiow through said armature, a relay for actuatingsaid switching means having the coil thereof connected in the platecircuit of a gas tube, a. feed-back circuit for impressing a negative A.C. voltage upon the grid of said tube, means for impressinga negative D.C. voltage upon said grid, and means responsive to rotation of saidarmaturefor impressing an A. C. voltage upon said. grid forcounteracting said feed-back ture of'a motor to oscillate through an arccomprising'switching means for reversing the direction of current fiowthrough said armature, a relay for actuating said switching means havingthe coil thereof connected in the plate circuit of a gas tube, afeed-back circuit connecting the movable arm of said relay and the gridof said gas tube, means for impressing a negative D. C. voltage uponsaidgrid; and means responsive to rotation of said armaturefor'counteracting th voltage impressed, upon said grid by said'feedbackcircuit.

3. An. electrical systemfor causing the armature of. a motor tooscillate through. an are comprising switching means for reversing thedirection of current flow through said armature, a relay for actuatingsaidaswitchin means having the coil thereof connected in the platecircuit of a. gas tube, a feed-back circuit connecting the movable. armof relay and the grid of said tube, means .disposedin said feed-backcircuit for. varying the voltage impressed by said circuit on said grid,means for impressi g a negative'D'. C.voltage on said grid, and meansresponsive to rotationof said armature for impressing a voltage on saidgrid having an amplitude proportional to said rotation for counteractingsaid 'feed-back voltage and said D. C. voltage bias,

4. Anelectrical system forcausing the armature of a motor to oscillatethrough an are comprising switching means for reversing the direction ofcurrent flow through said armature, a

. relay for actuating said switching means having the coil thereofconnected-in the plate circuit of a gas tube, a feed-back. circuitconnecting the movable arm of said relay and the grid of said tube,means disposed in said feed-back: circuit for varying the voltageimpressed by said circuit upon said grid, means for impressing anegative D. C. voltageupon said grid having an amplitude proportional torotation of said armature for counteracting said feed-back voltage andsaid D. C. voltage thereby causing energization of said relay, saidrelay being adapted to reverse the polarity of said feed-back voltageenergization and deenergization thereof.

5. Anelectrical system for causing the armature of a motor to oscillatethrough an are comprising switching means for reversing the directionofcurrentfiow through said armature, a relay for actuating said switchingmeans having said plate, a. feed-back circuit l connecting the movable,arm of said relay .and the control grid of said gas tube, said relaybein adaptedto reverse the p'olarity'of saidffeed-back circuit upon energization and. deenergization thereof, means disposed in said iced-backcircuit for varying the voltage impressed upon said grid, me'ansforimpressing aD. C. voltage upon said grid, and means responsive torotation of said armature for impressing an A. C. voltage upon said gridhaving an amplitude proportional to rotation of said armature forcounteracting said feed-back and D. C. voltages thereby causingenergization and deenergization of said relay.

6. An electrical system for causing the armature of a motor to oscillatethrough an are comprising switching means for reversing the direction ofcurrent flow through said armature, a relay for actuating said switchingmeans having the coil thereof connected in the plate circuit of a gastube, means for impressing a voltage on said plate, a feed-back circuitconnecting the movable arm of said relay and the control grid of saidtube, said relay being adapted to reverse the phase of said feed-backcircuit voltage upon energization and deenergization of said relay,means disposed in said feed-back circuit for varying the voltageimpressed thereby upon said grid, means for impressing a negative D. C.bias upon said grid, means for varying the centerpoint about which saidarmature is to be caused to oscillate, and means responsive to rotationof said armature for impressing an A. C. voltage upon said grid havingan amplitude proportional to the amount of rotation of said armature forcounteracting said feed-back and D. C. voltages, thereby causingalternate energization and deenergization of said relay.

7. An electrical system for causing an antenna to scan cyclicallythrough a given are comprising an electric motor for driving saidantenna, switching means for reversing the direction of current flowthrough the armature of said motor, a relay for actuating said switchingmeans having the coil thereof connected in the plate circuit of a gastube, means for impressing a voltage on said plate, a feed-back circuitconnecting the movable arm of said relay and the control grid of saidtube, said relay being adapted to reverse the phase of said feed-backcircuit voltage upon energization and deenergization of said relay,means disposed in said feed-back circuit for varying the voltageimpressed thereby upon said grid, means for impressing a negative D. C.voltage upon said grid, means for varying the centerpoint about whichsaid armature is caused to oscillate, and means responsive to rotationof said antenna for impressing an A. C. voltage upon said grid having anamplitude proportional to the amount of rotationof said antenna forcounteracting said feed-back and D. C. voltages, thereby causingalternate energization and deenergization of said relay with a resultantreversal of the direction of rotation of said antenna.

8. An electrical system for causing the armature of a motor to oscillatethrough an are comprising switching means for reversing the direction ofcurrent flow through said armature, means for actuating said switchingmeans connected in the plate circuit of an electron tube, a feed-backcircuit connecting said actuating means and the grid of said electrontube, means for impressing a negative voltage upon said grid,

,and meansiresponsive to rotation of said armature for counteracting thevoltage impressed upon said grid by said feed-back circuit.

posite directions froml a reference point, the

combination" comprising [a reversing motor for mparting movement tosaid-object, a gas filled rectifier for controlling the operation of'said motor,'said motorbeing operable in one direction whensaidrectifier is conducting and in a reverse direction when said rectifieris cut off, said rectifier havingfa control grid, and circuit means forsupplying a' biasing potential to said'grid varying with the position ofsaid object, said biasing potential being operative to render saidrectifier conductive when said object moves to one end of said path andto cut ofi said rectifier when said object moves to the other end ofsaid path.

10. A scanning system comprising a source of voltage having a movableelement, reversible driving means adapted to displace said element ineither of two directions for varying the output voltage of said sourcein one sense or another, respectively, a relay having contacts adaptedto reverse said driving means, an energizing circuit for said relay, anelectronic discharge device in said circuit, said device having an inputconnected across the output of said source, biasing means arranged inthe non-conductive condition of said device to render the sameconductive when the said output voltage reaches a first predeterminedlimiting value toward which it is being driven in the non-conductivecondition of said device, and bias modifying means arranged in theconductive condition of said device to maintain the same effectivelyconducting until the said output voltage reaches a second predeterminedlimiting value toward which it is being driven in the conductivecondition of said device.

11. A scanning system comprising a source of variable voltage having amovable element, an electronic discharge device having an inputconnected across the output of said source, re versible driving meansadapted to displace said element in either of two directions for varyingthe output voltage of said source in one sense or another, respectively,said driving means being responsive to the conductive and thenon-conductive condition of said device for displacing said element in arespective direction, first biasing means arranged to be eiTective inthe non-conductive condition of said device for maintaining the samesubstantially non-conductive until said output voltage reaches a firstpredetermined value, and second biasing means arranged to be efiectivein the conductive condition of said device for maintaining the samesubstantially conductive until said output voltage reaches a secondpredetermined value.

12; In a reversing drive for moving an object back and forth along apath extending in opposite directions from a reference point, thecombination comprising a reversing motor for imparting movement to saidobject, means for producing an alternating voltage having a potentialvarying with the distance of said object from said reference point, saidalternating voltage when said object is on one side of said referencepoint having a phase displacement of with respect to the alternatingvoltage produced when said object is on the other side of said referencepoint, control means for reversing the operation of said motor toreverse the movement of said object, and means responsive to saidalternating voltage for operating said control means each time saidobject moves to an end. of

said path.

13. A reversing drive as claimed in claim 12 in which theposition ofsaid referencepoint is adjustable to thereby change the position of thepath along which said object moves.

14. In a reversing drive for moving an object Ioackv and forth along apath extending in opposite directions from a. reference point, thecombination comprising a reversing motor for imparting movementto saidobject, a gas filled rectifier for controlling the operation of saidmotor, said motor being operable in one direction 8 when said. rectifieris conducting and in a reverse direction. when said rectifier is cut011, said rectifier havingv a control grid, means operable when saidrectifier is cut off for applying a constant alternating potential tosaid control grid for preventing condnction by said rectifier, and meansresponsive to movement of said object, to an end oi said path forreducing said potential to a value at which said rectifier is renderedcon- 10 ductive.

. No references cited.

